In pure electric vehicles designed to use a battery as an energy source, and engine hybrid electric vehicles and fuel-cell hybrid vehicles designed to use a battery as an energy buffer, the battery is one of the principal constituent elements for determining vehicle quality.
Therefore, a Battery Management System (BMS), which is configured to manage overall conditions of the battery, prevents early reduction in battery lifespan and transmits State of Charge (SoC) information of the battery to a vehicle controller configured to perform integrated control, thereby supporting electricity generation control and vehicle traveling control.
The principal function of the BMS may be to perform SoC estimation and a fully charged state of the battery, balanced voltage maintenance between cell modules, maximum charging and discharge voltage control based on battery SoC information, safety management, cooling control, and the like.
The amount of electric energy stored in the battery of the electric vehicle may denote an available range of the electric vehicle. In order to increase the range of electric vehicles, many electric vehicle manufacturers mainly increase battery capacity or enlarge an available SoC region of the battery.
The battery may have different performances according to battery temperature. Generally, a lithium (Li) battery has high resistance at a low temperature. Accordingly, since high resistance occurs when the battery is charged with electricity at a low temperature, the battery may be charged with a smaller charge as compared to the case in which the battery is charged with electricity at a normal or high temperature. In the electric vehicles, reduction in the electric charge stored in the battery may indicate reduction in the range of the electric vehicle.